Overbased metal sulfonate complexes and mineral oil compositions containing the same



United States Patent 3,436 347 OVERBASED METAL SULFONATE COMPLEXES AND MINERAL OIL COMPOSITIONS CONTAIN- INC THE SAME Ferdinand P. Otto and Richard S. Herd, Woodbury, N.J.,

assignors to Mobil Oil Corporation, a corporation of New York No Drawing. Filed May 23, 1963, Ser. No. 282,548

Int. Cl. Cn1 1/40 U.S. Cl. 252--33.3 22 Claims This invention relates to certain improved oil soluble, overbased, metal sulfonate complexes and to novel methods for preparing them. The invention is further directed to lubricating oils containing these complexes.

It is well known that lubricating oils tend to deteriorate under conditions of present-day diesel and automotive engines with attendant formation of sludge, lacquer, and resinous materials which adhere to the engine parts, particularly the piston rings, grooves, skirts, etc. Acidic components are formed in engines as a result of either the oxidation of the oil or the interaction of the oil with acidic compounds produced by fuel combustion. Such acidic deposits are a particular problem in diesel engines, especially marine diesels, wherein high sulfur content fuels are employed with the resulting formation of acidic combustion products which can cause corrosive wear. Indeed, it is generally recognized that the action of sulfur acids on cylinder walls is a principal cause of excessive wear rates.

To counteract the formation of the deposits in the engines, and to neutralize as far as possible these acidic components, certain chemical additives have been found which possess increased detergent characteristics and basicity and are therefore useful in helping maintain engines in clean and efficient operating conditions for extended periods of time.

Particularly preferred chemical additives of this type are compounds which may be referred to as oil-soluble metal carbonateoverbased metal sulfonate complexes or salts. These additives are prepared by the reaction of metal sulfonates with basic metal carbonate complexing reagents and contain an overbase or alkaline reserve supplied by the basic metal carbonate. Their metal content is significantly higher than the metal content of normal metal sulfonate salts, i.e., salts having metal contents equivalent to the acid-hydrogen content of the respective sulfonic acids from which they are derived. For example, they may contain metal contents of 100 percent up to 1000 percent or higher above those of the normal sulfonate salts. In general, this excess basic metal content or alkaline reserve functions to neutralize acidic components such as sulfur acids which are formed in the engine in an effort to thereby cut down the formation of solid deposits and corrosive wear.

These metal carbonate-overbased metal sulfonates, however, have not been completely satisfactory additives for remedying the problems of the deposition of solid products and of corrosive wear, especially at high temperatures. This is particularly the case with regard to marine diesel engines wherein significant port clogging occurs even when these complexes are used in the lubricating oil.

It is therefore an object of the present invention to provide improved overbased metal sulfonate complexes which when used as adidtives in mineral oil lubricants, inhibit the deposit forming tendencies, increase the high temperature oxidation stability of the lubricant and act to decrease excessive engine wear rates.

A further object is to provide overbased, metal sulfonate complexes containing a high content of a metal formate overbase.

A further object is to provide a novel, economical and effective process for producing these overbased, metal sulfonate complexes from metal carbonate-overbased metal sulfonate salts or complexes.

Another object is to provide mineral lubricating oils processing improved detergency, deposit forming inhibiting, high temperature oxidation stability and wear reducing characteristics.

Further objects of the invention and the advantages derived therefrom will become apparent hereinafter.

Broadly stated, it has been found that by subjecting metal carbonate-overbased, metal sulfonate salts or complexes to a reaction with formic acid, metal formateoverbased metal sulfonate salts or complexes are produced which contain a high metal formate content and are improved additives for mineral lubricating oils. The formic acid is employed in sufiicient proportions to substantially completely convert the metal carbonate component of the metal carbonate-overbased metal sulfonate complex to metal formate.

It should be noted at this point that the overbased, metal sulfonate products which are reacted with the formic acid may be interchangeably referred to as either metal sulfonate-metal carbonate complexes, metal sulfonate-metal carbonate salts, metal carbonate-overbased metal sulfonates, metal sulfonate-metal carbonate dispersions, or the like. Similarly, the products of the present invention obtained from the formic acid reaction may be described as either metal sulfonate-metal formate complexes, metal sulfonate-metal formate salts, metal formateover-based metal sulfonates, metal sulfonate-metal formate dispersion, or the like. The precise structure of the metal formate-containing products of the instant invention is not known. Without limiting the invention .to any particular theory, it is believed that two components form a complex addition product of the dispersion or colloidal suspension type wherein the metal formate is held in dispersion or suspension by the metal sulfonate.

For the sake of simplicity, the products of the present invention and the overbased metal sulfonates from which they are obtained, will hereinafter be referred to using terminology such as metal sulfonate-metal carbonate complexes or metal carbonate-over-based metal sulfonate complexes and metal sulfonate-metal formate complexes or metal formate-overbased metal sulfonate or similar expressions.

A variety of overbased, metal sulfonate-metal carbonate complexes, which are suitable for use in the formic acid reaction of the present invention, are shown in the art. Typical of these and, indeed, preferred, are the metal carbonate-overbased metal sulfonate complexes described in U.S. Patent Nos. 2,616,911 and 2,956,018.

As disclosed in U.S. Patent No. 2,956,018, these metal carbonate-overbased, metal sulfonates may be prepared by admixing an inorganic compound of a basic metal such as an alkaline earth metal oxide or hydroxide with an aliphatic monohydric alcohol containing 1 to 5 carbons such as methanol. A metal carbonate complexing reagent is then formed by passing carbon dioxide through this admixture of the basic metal compound and the aliphatic alcohol. This metal carbonate complexing reagent is reacted with a sulfonic acid or sulfonic acid salt to form the metal carbonate-overbased metal sulfonate complex, which is reacted with the formic acid according to the present invention.

In view of the fact that calcium sulfonate-calcium carbonate complexes are of special interest, the following is a further more specific description of the preparation of calcium sulfonate-calcium carbonate complexes which may be used in the preparation of the high metal content overbased, metal sulfonates of the present invention.

The formation of the calcium sulfonate-calcium carbonate complexes involves the preparation of a calcium carbonate complexing reagent in methanol and the reaction of this complexing agent with a sulfonic acid or sulfonate salt. The resulting calcium sulfonate-calcium carbonate is then reacted with formic acid to form our metal formate-overbased complexes.

More particularly, the aforementioned calcium carbonate complexing agent may be prepared by carbonating with carbon dioxide a suit-able calcium inorganic compound such as calcium oxide or hydroxide in methanol. For example, the complexing reagent may be prepared by first forming a suspension of the calcium compound, e.g., calcium hydroxide in absolute methanol, adjusting the temperature of this suspension to below approximately 30 C., preferably so that amount of carbon dioxide absorbed is such as to provide a mol ratio of carbon dioxide to calcium therein of from about 0.6 to about 2.0.

The resulting calcium carbonate complexing reagent is then reacted with a suitable sulfonic acid or metal salt thereof as follows. The chilled (l30 C.) complexing reagent is intermixed with a solution of the sulfonic acid or salt in mineral oil and the mixture is heated to a temperature above the boiling point of methanol to facilitate reaction and effect removal of the methanol by distillation. After the distillation step, the reaction mixture is filtered, preferably while hot, to provide the high metalcontent calcium sulfonate-calcium carbonate complex.

A sufiicient amount of mineral oil is preferably employed as solvent in the reaction between the calcium carbonate complexing reagent and the sulfonic acid or salt in order to maintain the reaction mixture fluid and thus facilitate the final filtration and handling of the product which would otherwise be quite viscous. Other hydrocarbon solvents besides mineral oil or in addition to mineral oil, such as light naphtha, xylene, toluene, benzene, etc., may be employed.

The amount of calcium carbonate complexing reagent employed in the reaction with the sulfonic acid or salt should, of course, be sufficient to provide the excess metal which is incorporated into the complex salt product. Thus, at least about 3 equivalents and up to about ll equivalents or more of calcium should be provided in the complexing reagent where the sulfonic acid per se (i.e., unneutralized) is used and at least about 2 equivalent and up to about or more of calcium, Where a neutral sulfonic acid salt is utilized in the process, the said equivalents being on the basis of the acid-hydrogen equivalents of the sulfonic acid or the neutral sulfonic acid salt.

The sulfonic acids from which the calcium sulfonatecalcium carbonate intermediates are prepared, or, indeed, any of the metal sulfonate-metal carbonates, include oilsoluble petroleum and synthetic alkaryl sulfonic acids, particularly those having molecular weights of from about 300 to about 800. These acids may be produced by sulfonation of petroleum stocks or synthetic alkyl aromatic compounds, such as alkyl substituted benzenes or a naphthalenes, wherein the alkyl groups attached to the aromatic ring contain from at least about 14 to about 24, or more, carbon atoms. Suitable synthetic sulfonic acids are, for example, octadecyl-benzene sulfonic acid. Of the various acids, the wax benzene and wax-naphthalene sulfonic acids and mixed alkyl aromatic sulfonic acids are preferred. The petroleum sulfonic acids, also known as sour oils", are those obtained in the treatment of petroleum oils, particularly refined or semi-refined oils, with concentrated or fuming sulfuric acid, and which remain in the oil after settling out of the sludge.

These sulfonic acids may be represented by the general formula:

R SOaH where R is one or more alkyl, alkaryl or aralkyl groups and the aromatic nucleus is a single or condensed ring or partially hydrogenated ring.

Although the preparation of calcium carbonate-overbased, calcium sulfonate complexes has been referred to in some detail, it should be noted that the present invention is applicable to any Overbased, metal sulfonate complex containing a metal carbonate as the overbase material wherein the metal is an alkaline earth metal. It will also be appreciated that any of this type of metal carbonateoverbased, metal sulfonate complexes may be employed in the formic acid reaction regardless of their particular method of preparation.

Overbased, metal carbonate-metal sulfonate complexes, wherein the metal is an alkaline earth metal such as Ca, Ba, Sr, are of particular interest.

The novel metal sulfonate-metal formate complexes are, as mentioned above, obtained by reacting the corresponding metal sulfonate-metal carbonate complex with formic acid. Sufiicient amounts of formic acid are employed in order to convert substantially all of the basic carbonate to the formate. Thus, at least one chemical equivalent of formic acid per equivalent of carbonate in the overbased, metal sulfonate-metal carbonate complex is employed.

The reaction with the formic acid is conducted at slgihtly elevated temperatures. For example, temperatures in the range of from about 50 to about 225 C., preferably from about to about 200 F. are suitable.

The metal sulfonate-metal formate reaction product may be recovered in any suitable manner, such as by filtration wherein the desired reaction product is recovered as the filtrate.

According to a particular aspect of the process of the present invention, it has been found that superior filtration results are obtained by adding a small amount of a sulfonic acid to the formic acid used in the reaction step. The sulfonic acid is added to the formic acid to be used in the preparation of the metal formate-containing products, and this mixture of acids is introduced into the reaction zone. It is advisable to employ a subsurface addition procedure whereby the mixed acids are introduced below the surface of the other reactants. The use of the sulfonic acid in this manner results in extremely rapid filtration rates.

We have also found that the rate of filtration is further improved if the formating of metal sulfonate-metal carbonate is conducted at temperatures from about 150 to about 200 0, preferably about 200 C.

Any sulfonic acid may be mixed with the formic acid. For example, sulfonic acids such as those hereinabove mentioned as suitable for use in the preparation of the metal sulfonate-metal carbonate complexes may be employed.

The amount of the sulfonic acid employed will vary depending upon the proportions of the other reactants. In general, small amounts from about 0.6 percent to about 2.5 percent, based on the total CO present in the metal carbonate-overbase metal sulfonate, are employed. Although of course, this aspect of the invention is not to be limited to any particular theory, it is believed that the presence of the sulfonic acid in the reaction mixture promotes the resolubilization of the insoluble metal formates and metal carbonates which may come out of solution and tend to prevent good filtration results.

The metal formate-overbased metal sulfonate of this invention possess additive properties superior to those of the corresponding metal carbonate-overbased metal sulfonates. Thus, our metal formate products inhibit the deposit-forming tendencies, increase the high temperature stability and improve the anti-wear properties of lubricating oils to a significantly greater extent than do the corresponding metal carbonate products.

The criticality of the metal formate components is also demonstrated by the fact that the corresponding metal acetate-overbased metal sulfonates are jell-like, insoluble masses, unsuitable for use in lubricating oils.

The metal formate-overbased metal sulfonate complexes of the invention are further distinguishable from metal sulfonate complexes heretofore known, by virtue of their exceedingly high metal contents. Thus, the metal contents of our metal formate-overbased complexes are from 200 percent up to about 1000 percent or more, higher than that of the corresponding normal salts, i.e., salts having metal contents equivalent to the acid hydrogen contents having the respective sulfonic acids from which they are derived.

The production of metal formate-overbased metal sulfonates contianing such high metal contents is due to the specific procedure utilized in our synthesis. According to this aspect of the invention, the metal formate is in troduced by going through the carbonate group of the metal carbonate-overbased metal sulfonate, that is, by first forming the metal carbonate-overbased product and then converting this product to a metal formate-overbased complex by reaction with formic acid. The importance of this specific process procedure becomes apparent when it is realized that metal sulfonate-metal formate complexes such as calcium sulfonate-calcium formate complexes possessing metal contents from 200 percent up to 1000 percent or more higher than that of the corresponding normal salt, as far as we are aware, cannot be prepared directly from a sulfonic acid or calcium sulfonate and a calcium formate. According to the best of our knowledge, only by carrying out the instant formic acid reaction is it possible to produce such extremely high metal content calcium sulfonate-calcium formate complexes, since there is believed to be no other effective way of introducing such amounts of calcium formate other than by going through the carbonate group.

These metal sulfonate-metal formate complexes are of particular interest as additives for marine diesel cylinder lubricants wherein they inhibit the deposit-forming tendencies especially the port clogging tendencies which result from the use of high sulfur content fuels in these engines, and act to improve the anti-wear characteristics of the lubricating oils. These metal formats-overbased complexes may also be used, for example, in lubricating oils for railroad diesel engines, gas engines, as well as in as various other types of lubricants for internal combustion engines. It will be appreciated, however, that the complexes of the present invention may be advantageously used in a variety of mineral oil lubricating compositions.

The particular amounts of the metal formate-overbased sulfonate complex used in the mineral oil compositions will depend on factors such as the nature of the base oil, its intended use, the presence of other ingredients, etc. In general, the overbased sulfonate complex may be present in an amount from about 1 to 40 percent by weight of the oil. In the case of marine diesel oils higher proportions in the range of from about to 40 percent, preferably to percent are used. On the other hand, in automotive engines oils, 1-10 percent, preferably 5-10 percent of the additive may be used.

It will of course, be appreciated that the mineral oil compositions containing the instant overbased sulfonate complex may, of course, also contain effective quantities of various other typical lubricating oil additives, such as pour point depressants, V.I. improvers, extreme pressure agents, anti-oxidants, etc.

The following examples are presented to illustrate more clearly the nature of the present invention. It should be understood, however, that the invention is not limited to these specific embodiments.

Example 1 shows the procedure for the preparation of a calcium sulfonate-calcium carbonate complex which is of the type reacted with formic acid in the succeeding working examples.

6 EXAMPLE 1 A slurry of 148 grams (4.0 true equivalents) of calcium hydroxide in two liters of absolute methanol was charged into a 5-liter flask, chilled below 15 C. in an ice-bath and carbonated to a carbon dioxidezcalcium ratio of 1.9 (162 grams, 7.4 equivalents of C0 The slurry thickened considerably during the carbonation. The rate of carbonation was followed by noting the increase in weight of the reaction flask.

A mixture of 600 grams (0.67 true equivalents) of a mixed wax-benzene (2-12)-alkyl aromatic sulfonic acid having a total N.N. of 68 and a true N.N. of 63 and 600 grams of diluent oil (a parafiinic oil having a viscosity of SUS at 100 F.) was heated in a beaker to 60 C. and added to the complexing reagent.

The methanol was removed through a Dean-Stark takeoff by heating the reaction mixture to 90 C. over 6% hours and then maintaining the temperature at 90-100" C. for 1% hours with vigorous nitrogen blowing.

Sixty grams of Hyflo (a diatomaceous earth filter aid) were added and the mixture filtered through an electrically heated Biichner funnel precoated with Hyflo giving a bright fluid product having the following analysis:

Calcium (total) percent 5.3. Perchloric acid base No. (mg.

KOH/g. sample) $4.3% calcium. Excess calcium percent 430.

EXAMPLE 2 One hundred grams (424.7 g. C0 0.22 equivalents CO of a calcium sulfonate-calcium carbonate complex (5.1% Ca, 4.7% C0 119 TBN (Total Base Number), and prepared according to Example 1) were charged into a 250 ml., 4-neck, round bottom flask equipped with a mechanically driven glass paddle, stirrer, thermometer and nitrogen inlet tube. The charge was warmed to 90 C. and 6 grams (0.118 equivalents) of formic acid (90.5% assay) were added dropwise. The temperature was raised to C., in a stream of nitrogen, for ten minutes. The mixture was cooled to 90 C. and 4 grams (.079 equivalents) of formic acid (90.5 %assay) added dropwise. The temperature was raised to C., in a stream of nitrogen, and held there for 1 hour. The product was filtered through diatomaceous earth on a heated Biichner funnel and analyzed as follows:

Analysis of product: Percent Calcium 4.5 Formic acid 9.0 Carbon dioxide 0.56 Perchloric acid base no.

(mg. KOH/g. sample) 109 1 (As combined calcium-f0rmate.)

EXAMPLE 3 Five hundred grams (323.5 g. C0 1.07 equivalents CO of a calcium sulfonate-calcium carbonate complex (5.1% Ca, 4.7% C0 119 TBN, and prepared according to Example 1) were charged into a 1000 ml., 4-neck, round bottom flask equipped with a mechanically driven glass paddle stirrer, thermometer and dropping funnel. The charge was warmed to 90 C., and 49.5 g. of formic acid (0.97 equivalents) (90.5% assay) were added dropwise over a period of 40 minutes. After the addition of formic acid, the temperature was raised to 150 C. and held for 1 hour in a stream of nitrogen. Twenty-five grams of diatomaceous earth were added to the mixture and then filtered through diatomaceous earth on a heated Biichner funnel.

Analysis of product: Percent Calcium 4.47 Forrnic acid 7.9 Carbon dioxide 1.04 Perchloric acid base No.

(mg. KOH/g. sample) 111 7 EXAMPLE 4 Five thousand grams ($210 g. CO 9.5 equivalents CO of a calcium sulfonate-calcium carbonate complex (4.9% Ca, 4.2% C 112 TBN, and prepared according to Example 1) were charged into a 12 liter, 4-neck, round bottom flask equipped with a mechanically driven glass paddle stirrer, thermometer, reflux condenser and drop ping funnel. The charge was warmed to 85 C. and 510 grams (10.0 equivalents) (5% in excess of the amount required to convert all the basic carbonate to formate) of formic acid (90.5 assay) were added dropwise over a period of 48 minutes. The temperature was raised to 150 C. in a stream of nitrogen. The product was held at 150 C. for 0.5 hour under reduced pressure (approx. 200 mmg.) The product was cooled to 120 C. in a stream of nitrogen, treated with 300 g. of diatomaceous earth and filtered through diatomaceous earth on a heated Biichner funnel.

Analysis of product:

Calcium percent 4.5 Formic acid do 7.9 Carbon dioxide do 0.8

Perchloric acid base No., mg. KOH/ g. sample 102 EXAMPLE 5 Five hundred grams ($21g C0 0.95 equivalents CO of a calcium sulfonate-calcium carbonate complex (4.9% Ca, 4.2% C0 112 TBN and prepared according to Example l) were charged into a 1000 ml., 4-neck, round bottom flask equipped with a mechanically driven glass paddle stirrer, thermometer, reflux condenser and dropping funnel. The charge was warmed to 85 C. and 46 grams (0.905 equivalents) (the amount required to convert 95% of the basic carbonate to formate) of formic acid (90.5% assay) were added dropwise over a period of 45 minutes. The temperature was raised to 150 C., in a stream of nitrogen, and held for 1 hour. The product was cooled to 120 (3., treated with 25 grams of diatomaceuos earth and filtered through diatornaceous earth on a heated Biichner funnel.

Analysis of product:

Calcium percent 4.6 Formic acid do 7.7 Carbon dioxide do 0.9

Perchloric acid base No. $102 mg. KOH/ g. sample.

EXAMPLE 6 One thousand grams (106 grams CO or 4.82 CO equivalents) of an overbased calcium sulfonate-calcium carbonate product (10.6% C0 299- TBN, 11.9% Ca) were charged into a 2 liter, 4-neck round bottom flask equipped with a mechanically driven glass paddle type stirrer, thermometer, special dropping funnel (adapted for subsurface addition), and special water receiver (adapted for nitrogen sparge inlet and condenser). The charge was warmed to 200 C. with a nitrogen sparging rate of 1 cubic foot per hour and held for 1 hour. A mixture containing 268 grams (5.25 equivalents, 10% in excess) of formic acid (90% assay) and 52 grams (0.06 equivalents) of waxbenzene high boiler sulfonic acid (TBN 65) was added to the charge in four portions. Each portion was added over a period of one hour with a half hour hold period in between additions. After the final addition, the reaction was held for one hour. 560 grams of the reaction product was treated with 5% (28 grams) of diatomaceous earth on a heated Biichner funnel.

Analysis of product:

Calcium percent 1 1.0 Formic acid do 20.8 Carbon dioxide do 1.3 Perchloric acid base No mg. KOH/g 285 KV 210 F., cs "percent" 55.05

8 EXAMPLE 7 Three thousand grams (318 grams CO or 14.46 CO equivalents) of an overbased calcium sulfonate-calcium carbonate product (10.6% C0 299 TBN, 11.9% Ca) were charged into a 5 liter, 4-neck round bottom flask equipped the same as in Example 6. A mixture containing 803 grams (15.75 equivalents, 10% in excess) of formic acid assay) and 155 grams (0.18 equivalents) of waxbenzene high boiler sulfonic acid (TBN 65) was added to the charge using a procedure similar to Example 6.

Analysis of product:

Calcium percent 11.3

Formic acid do 22.9

Carbon dioxide do 1.4

Perchloric acid base No mg. KOH/g 290 KV 210 F., cs -.percenL. 66.30

EXAMPLE 8 The same procedure as that of Example 6 was followed except 270 grams (5.3 equivalents) of formic acid was used without the waxbenzene high boiler sulfonic acid.

Analysis of product:

Calcium percent 11.4

Formic acid do 22.9

Carbon dioxide d0 1.1

Perchloric acid base No mg. KOH/g 294 KV 210 F, cs. percent 56.93

EXAMPLE 9 The same procedure as that of Example 8 was followed, except the reaction temperature was C. instead of 200 C.

This example illustrates a product prepared at a high temperature (intermediate range) without the use of waxbenzene high boiler sulfonic acid.

Comparative tests To demonstrate the superior deposit forming inhibiting characteristics of the instant metal sulfonate-metal formate complexes and especially their superiority over known metal sulfonate-metal carbonate complexes, several lubricating oil formulations, as shown in the following Table I, were subjected to a Panel Coker Test. The comparison was conducted on a base oil containing a calcium sulfonate-calcium formate complex described in the preceding examples.

Panel coker test This well-known test, which is used to determine the tendency of lubricants to form solid decomposition products when in contact with high temperature surfaces, is indicative of the high temperature oxidation stability of an oil.

In accordance with this test, a sample of a lubricant is splashed upon a tared, polished aluminum test panel. The test panel is heated and placed in the coking apparatus in a position such that the polished surface thereof is exposed to contact with oil thrown against it by means of a splasher immersed in the oil. The test panel is heated to a temperature of 600 F. and maintained at this temperature while the splasher is on and off operated for a period of 24 hours. The splasher operates 15 seconds out of every minute. After the test, the panel is removed, cooled, washed, dried, and re-weighed. The dilference in weight before and after the test is the amount of solid combustion deposits and is indicative of the high temperature oxidation stability of an oil.

9 Table I. Panel coker test (24 hours at 600 F.)

Deposit Formulation Weight, mg.

(1) Base Stocks +32% calcium sulfonate-calcium carbonate complex 22 (2) Base Stocks +38.2% calcium sulfonate-calcium formate complex of Example 4 Nil (3) Base Stocks +27.2% calcium sulfonate-calcium carbonate complex +5. sulfurized calcium phenate-calcium carbonate 50-150 (4) Base Stocks +27.2% calcium sulfonate-calcium formate complex of Example 3+5.0%

sulfurized calcium phenate calcium carbonate Nil (5) Base Stocks +'31.4% calcium sulfonate-calcium formate complex of Example 4+5.0%

sulfurized calcium phenate calcium carbonate Nil Formulated for a 40 TBN oil.

45% Solvent Refined Coastal Bright Stock (150-160 SUV 210 F.) +55% Solvent Refined Coastal Distillate Stock (55430 SUV 210 F.).

0 Calcium sulfonate-calcium carbonate complex produced according to Example 1.

Sulfurized calcium phenate-calcium carbonate complex prepared according to U.S. Patent No. 3,036,971. (Typical analysis: 5.2% Ca, 3.2% C02, 146 TBN.)

Marine port clogging test The ability of the overbased calcium sulfonate-calcium formate product of this invention as an additive in marine diesel cylinder oils is shown by a comparative test in a Marine Port Clogging Test. The comparision was conducted on a base oil containing an overbased calcium sulfonate-calcium carbonate and an overbased calicum sulfonate-calcium formate. The results are shown in Table II.

Outline of method A Marine Port Clogging Test apparatus was fabricated and operating variables were studied at a set of conditions that would produce port deposits in a short period of time. With the test conditions arrived at, as summarized in the table below, we have a 6 hour test that will differentiate between different types of marine cylinder lubricants.

Essentially the test apparatus consists of four parts:

(1) A motored Homelite 2-cycle engine.

(2) An external lubricating system to meter the test lubricant through three points around the Homelite cylinder.

(3) A fuel oil burner to produce combustion gases.

(4) A duct system to guide the exhaust gases from the burner through the exhaust ports of the Homelite engine.

In this test the experimental oil is fed above the exhaust ports of the 2-cycle engine cylinder while sooty exhaust gases from the combination diesel fuel are deflected into the cylinder. The motored piston covers and uncovers the exhaust ports, spreading the oil around the cylinder.

The deposits formed are rated visually for amount of deposit port closure) and the type of deposit.

10 Marine port clogging test conditions Test duration, hours 6 Engine speed, r.p.m. 36 Fuel consumption, lbs/hr 1.45 Air/fuel ratio 1112 to l Preheater temp., F. 190-200 Exhaust temp., F. 700-800 Smoke level (Bacharach smoke scale) 10 X 9+ Oil feed rate, gms./hr. 27

Table II.Marine port clogging test results Formulation a Base oil b Percent port clogging +43% sulfurized calcium phenate-calcium carbonate +12.5% calcium sulfonate-calcium formate prepared according to Example 6 Base oil +43% sulfurized calcium phenate-calcium carbonate +11.8% calcium sulfonate-calcium carbonate 25 Formulated for a 40 TBN oil.

45% Solvent Refined Coastal Bright Stock (150-160 SUV 210 F.)+% Solvent Refined Coastal Distillate Stock 5-60 SUV 210 F.).

c Sulfurized calcium phenate-calcium carbonate complex prepared according to US. Patent No. 3,036,971. (Typical analysis: 5.2 ca, 3.2%CO 146 TBN).

As can be seen from the test results, the oil containing the calcium formate-overbased complex produced a port clogging of only 10%; while the oil containing the corresponding metal carbonate-overbased product produced a port clogging of 25%.

Filtration rate tests The improved rate of filtration achieved by the addition of a small amount of sulfonic acid to the formic acid used in the formating step is shown by the following rate test reported in Table III.

According to this test, the products of Example 6-9 (560 grams 5% diatomaceous earth) were heated to 150 C. and a Biichner funnel was heated to maintain the product at 150 C. The time necessary to completely filter each of these products was measured. The equipment employed and the filtration times are given below.

Table III.Filtration rate test Equipment:

Biichner funnel (Size 2A, 3.75" I.D.) Heating Mantle Suction flask Filter paper (topped with approx. /s" diatomaceous earth Product of Example No. Filtration, minutes 6 (Formated at 200 C. sulfonic acid) 22 7 (Formated at 200 C. sulfonic acid) l5 8 (Formated at 200 C.) 56 9 (For-mated at 150 C.)

It will be noted that the products of Examples 6 and 7, wherein a sulfonic acid was added to the formic acid prior to the formating step, required only 22 and 15 minutes respectively for complete filtration; whereas with the products of Examples 8 and 9, wherein no sulfonic acid was added, filtration times of 56 and more than 60 minutes respectively were needed.

Ship test data An oil containing a calcium sulfonate-calcium formate complex of this invention and a high grade, commercial marine oil were each tested in a ship equipped with Fiat diesels, for a period of about 1000 hours. The average percent port clogging observed in each case is reported in Table IV.

TABLE IV.PORT CLOGGING IN FIAT DIESEL ENGINE Average Formulation percent Hrs. of use port clogging (1) Commercial marine diesel oil 2 l8 1, 000 (2) Base oil 3 +l4.3% calcium sulfonate-calcium formats complex 4 9 946 l Formulated for a 40 'IBN oil.

2 Base Oil 5 +27.3% suliurized calcium phenate-calcium carbonate.

3 45% Solvent Refined Coastal Bright Stock (150-160 SUV at 210 F.) +55% Solvent Refined Coastal Distillate Stock (55-60 SUV at 210 F.)

Prepared according to working Example 6.

It will be noted that Formulation 2, which contained the calcium formate-overbased calcium sulfonate held the percent port clogging down to an average of 9%, whereas an average port clogging of 18% took place when the commercial marine diesel oil was employed.

Although the preparation and specific utilities of certain representative complexes, salts or dispersions and oil compositions containing them have been set forth in detail, it will be appreciated that the present invention is not in any way limited to these specific embodiments, but that suitable variations and modifications can be made therefrom without departing from the spirit and scope of the present invention.

Having thus described the invention, what we desire to secure and claim by Letters Patent is:

1. A process for preparing an oil-soluble, liquid metal formate-overbased metal sulfonate complex reaction product, the metal component of which is selected from the group consisting of barium, calcium and strontium and which possesses a metal content at least 200 percent higher than that of the corresponding normal metal sulfonate salt, which comprises reacting in liquid solvent a metal carbonate-overbased metal sulfonate complex, the metal component of which is selected from the group consisting of barium, calcium and strontium and which possesses a metal content at least 200 percent higher than that of the corresponding normal metal sulfonate salt, with formic acid in a proportion sufiicient to substantially completely convert the metal carbonate component of the metal carbonate-overbased metal sulfonate complex to metal formate.

2. The process of claim 1, wherein the metal component of said metal carbonate-overbased metal sulfonate complex and said metal formate-overbased metal sulfonate is calcium.

3. The process of claim 1 wherein the liquid solvent is a mineral oil.

4. The process of claim 1, wherein said reaction with formic acid is carried out at a temperature from about 50 to about 225 C.

5. The process of claim 1, wherein said reaction with formic acid is carried out at a temperature from about 150 to about 200 C.

6. A process for preparing an oil-soluble, liquid metal formate-overbased metal sulfonate complex reaction product, the metal component of which is selected from the group consisting of barium, calcium and strontium and which possesses a metal content at least 200 percent higher than that of the corresponding normal metal sulfonate salt, which comprises reacting in liquid solvent a metal carbonate-overbased metal sulfonate, the metal component of which is selected from the group consisting of barium, calcium and strontium and which possesses a metal content at least 200 percent higher than that of the corresponding normal metal sulfonate salt, with formic acid and a minor amount, sufficient to improve the filtration rate of the metal formate-overbased product, of a sulfonic acid, subjecting the reaction product to a filtration step and recovering the metal formate-overbased metal sulfonate complex.

7. The process according to claim 6, wherein said reaction is carried out a temperature from about 150 to about 200 C.

8. The process of claim 6, wherein said sulfonic acid is employed in an amount from about 0.60 to about 2.50 percent based on the CO content the metal carbonateoverbased metal sulfonate.

9. The process of claim 6, wherein said formic acid and sulfonic acid are introduced below the surface of the metal carbonate-overbased metal sulfonate.

10. As a new composition of matter, an oil-soluble, liquid metal formate-overbased metal sulfonate complex reaction product, the metal component of which is selected from the group consisting of barium, calcium and strontium and which possesses a metal content at least 200 percent higher than that of the corresponding normal metal sulfonate salt, obtained by reacting in liquid solvent a metal carbonate-overbased metal sulfonate complex, the metal component of which is selected from the group consisting of barium, calcium and strontium and which possesses a metal content at least 200 percent higher than that of the corresponding normal metal sulfonate salt, with formic acid in a proportion sufiicient to substantially completely convert the metal carbonate component of the metal carbonate-overbased metal sulfonate complex to metal formate.

11. The composition of claim 10, wherein said metal formate-overbased metal sulfonate complex is obtained by reacting said metal carbonate-overbased metal sulfomate with at least one chemical equivalent of formic acid per carbonate group of said metal carbonate-overbased metal sulfonate complex.

12. The composition of claim 10, wherein said metal formate-overbased metal sulfonate complex is obtained by reacting said metal carbonate-overbased metal sulfonate with formic acid at a temperature of from about 50 to about 225 C.

13. The composition of claim 10, wherein said metal formate-overbased metal sulfonate complex is obtained by reacting said metal carbonate-overbased metal sulfonate with formic acid at a temperature from about to about 200 C.

14. The composition of claim 10, wherein the metal component of said metal carbonate-overbased metal sulfonate complex and said metal formate-overbased metal sulfonate complex is calcium.

15. A mineral lubricating oil composition containing a minor proportion, sufiicient to improve the anti-wear characteristics, increase the high temperature oxidation stability and inhibit the deposit forming characteristics thereof, of an oil-soluble liquid metal formate-overbased, metal sulfonate complex reaction product, the metal component of which is selected from the group consisting of barium, calcium and strontium and which possesses a metal content at least 200 percent higher than that of the corresponding normal metal sulfonate salt, obtained by reacting in liquid solvent a metal carbonate-overbased metal sulfonate, the metal component of which is selected from the group consisting of barium, calcium and strontium and which possesses a metal content at least 200 percent higher than that of the corresponding normal metal sulfonate salt, with formic acid in a proportion sufiicient to substantially completely convert the metal carbonate component of said metal carbonate-overbased metal sulfonate complex to metal formate.

16. The composition of claim 15, wherein the metal formate-overbased metal sulfonate is present in an amount from about 1 to about 40 percent by weight.

17. The composition of claim 15, wherein said metal formate-overbased metal sulfonate is obtained by the reaction of the metal carbonate-overbased metal sulfonate with the formic acid at a temperature from about 50 to about 225 C.

18. The composition of claim 17, wherein said reaction of the metal carbonate-overbased metal sulfonate with formic acid is carried out at a temperature of from about 150 to 200 C.

19. The composition of claim 15, wherein the metal component of said metal carbonate-overbased metal sul- 13 fonate and said metal formate-overbased metal sulfonate is calcium.

20. A diesel mineral lubricating oil containing a minor proportion, suflicient to improve the anti-wear characteristics, increase the high temperature oxidation stability and inhibit the deposit forming characteristics thereof, of an oil-soluble liquid, metal formate-overbased metal sulfonate complex reaction product, the metal component of which is selected from the groups consisting of barium, calcium and strontium and which possesses a metal content at least 200 percent higher than that of the corresponding normal metal sulfonate salt, obtained by reacting in liquid solvent a metal carbonate-overbased metal sulfonate, the metal component of which is selected from the groups consisting of barium, calcium and strontium and which possesses a metal content at least 200 percent higher than that of the corresponding normal metal sulfonate salt, with formic acid in a proportion sufficient to substantially completely convert the metal carbonate component of said metal carbonate-overbased metal sulfonate complex to metal formate.

21. The diesel mineral lubricating oil composition of claim 20, wherein the metal component of said metal carbonate-overbased metal sulfonate complex and said metal formate-overbased metal sulfonate complex is calcium.

22. The diesel mineral lubricating oil composition of claim 20, which also contains a small amount of a sulfurized calcium phenate-calcium carbonate complex wherein the amount of said complex in admixture with the metal formate-over based metal sulfonate complex in a lubricating oil is sufficient to decrease the formation of deposits.

References Cited UNITED STATES PATENTS 2,762,773 9/ 1956 Palmer 25233.2 2,763,615 9/1956 Faust 25233 2,856,362 10/1958 Morway 25233.2 2,956,018 10/1960 Carlyle et a1 25218 3,027,325 3/1962 McMillen et al. 25218 X 3,036,971 5/1962 Otto 25242.7 3,178,368 4/1965 Hanneman 25218 X 3,242,079 3/1966 McMillen 25218 X FOREIGN PATENTS 776,455 6/1957 Great Britain.

PATRICK P. GARVIN, Primary Examiner.

US. Cl. X.R. 

20. A DIESEL MINERAL LUBRICATING OIL CONTAINING A MINOR PROPORTION, SUFFICIENT TO IMPROVE THE ANTI-WEAR CHARACTERISTICS, INCREASE THE HIGH TEMPERATURE OXIDATION STABILITY AND INHIBIT THE DEPOSIT FORMING CHARACTERISTICS THEREOF, OF AN OIL-SOLUBLE LIQUID, METAL FORMATE-OVERBASED METAL SULFONATE COMPLEX REACTION PRODUCT, THE METAL COMPONENT OF WHICH IS SELECTED FROM THE GROUPS CONSISTING OF BARIUM, CALCIUM AND STRONTIUM AND WHICH POSSESSES A METAL CONTENT AT LEAST 200 PERCENT HIGHER THAN THAT OF THE CORRESPONDING NORMAL METAL SULFONATE SALT, OBTAINED BY REACTING IN LIQUID SOLVENT A METAL CARBONATE-OVERBASED METAL SULFONATE, THE METAL COMPONENT OF WHICH IS SELECTED FROM THE GROUPS CONSISTING OF BARIUM, CALCIUM AND STRONTIUM AND WHICH POSSESSES A METAL CONTENT AT LEAST 200 PERCENT HIGHER THAN THAT OF THE CORRESPONDING NORMAL METAL SULFONATE SALT, WITH FORMIC ACID IN A PROPORTION SUFFICIENT TO SUBSTANTIALLY COMPLETELY CONVERT THE METAL CARBONATE COMPONENT OF SAID METAL CARBONATE-OVERBASED METAL SULFONATE COMPLEX TO METAL FORMATE.
 22. THE DIESEL MINERAL LUBRICATING OIL COMPOSITION OF CLAIM 20, WHICH ALSO CONTAINS A SMALL AMOUNT OF A SULFURIZED CALCIUM PHENATE-CALCIUM CARBONATE COMPLEX WHEREIN THE AMOUNT OF SAID COMPLEX IN ADMIXTURE WITH THE METAL FORMATE-OVERBASED METAL SULFONATE COMPLEX IN A LUBRICATING OIL IS SUFFICIENT TO DECREASE THE FORMATION OF DEPOSITS. 